I'd imagine a better way would be to heat the 7 liters incrementally, instead of all at once, this way it should be more efficient (faster).
I'd start with a fast drip/trickle feed, onto or into a preheated metal heat pipe.
Aim the concentrator at the heat pipe, until it good and hot, then open a valve to slowly allow the water in. This should flash boil the water, creating steam (which could run a turbine) which can then be directed to an insulated container which is then recirculated back through the heat pipe to be further heated. This should be a lot faster to heat the water than trying to heat it all at once.

I used a 7 liter pot because i had a 7 liter pot. And it is a a "keep it simple" solar cooking project. I wanted just to get water hot for soup or stew, etc. A turbine is not necessary.

Sure thing, believe me, i know ALL about using what i can scrounge up or have laying around! ;-)
Good on you for having the go in you to attempt this. I think it's great.
Just really thinking about others who may want to generate electricity using a similar system.
Another way, not using water at all, would be to focus the energy onto a small solar cell (a few inches square), this apparently can multiply the cells output by up to 1000 times! (youtube solar concentrator PV cell)
Happening in Israel at the moment. A guy has a parabolic concentrator made of individual small mirror (six inch i think), and directs the beam to a small PV cell, which he says increases the rated output of the cell by upto 1000 times!
Another method i was thinking of would be along the same lines of the above example, but instead of using a small PV cell, a was thinking of a bank of peltier devices with the 'cold' side in a water bath, and the concentrated light aimed on the 'hot' side...should work, unless the peltier is destroyed first with the intense heat.
Nice work gaiatechnician.

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<a rel="nofollow" href="http://www.youtube.com/watch?v=9eY0xh23Anc">http://www.youtube.com/watch?v=9eY0xh23Anc</a> is the making of a dome for a 45 degree compound solar dish. This dish is undergoing testing right now.<br/> 45 degrees acceptance angle should mean that it can cook for up to 3 hours without moving the dish.<br/>It is heating 7 liters of water in a pot . It has gone from 17C to 60C in 1 hr 41 minutes. (it is about 1154 am right now)<br/>